Abstract
Abstract Optical phase-locking has many important applications and has became an important tool in optics. We built a phase-lock loop with which is used to offset phase-lock two diode-pumped non-planar ring Nd:YAG lasers in the experiment of determining the accuracy of optical second harmonic generation. This study is important in the field of optical frequency metrology and we achieved a result of 10-16. Our approach basically base on the idea proposed by R. Wynands, et al. By measuring the beat frequency between the second harmonics and sum frequency generation, we set the upper limit of the deviation of 2:1 frequency ratio in optical second harmonic generation and the 10-16 result obtained is among the best in this area of study. A suggestion of further improvements toward 10-17 or better is also given in the end of this thesis.